The sea of clouds has an abundance of green crystals in the lower parts of the rocks, definitely wind crystals and possibly of the corrupted variety though I'm not sure of the visual difference if any. As for WHY they are there: If i remember the Vanu myth regarding Bismarck correctly it mentions the gods raising the sea of clouds into the heavens when they resurrected Bismarck. So I'm going to blame the Allagans.